Klunkerz is a fast-moving documentary that traces the global rise of mountain biking from its Marin County roots. An outgrowth of the Bay Area's late-'60s, early-'70s hippy counterculture, pot-smoking adrenaline junkies from Mill Valley, Larkspur and surrounding towns took their pre-World War II bicycles known as 'klunkerz', due to their fat tires, to the top of Mt. Tamalpais. They then hurled themselves down dirt paths, risking life and limb in search of a killer high. People formed amateur bike leagues and tricked-out their two-wheelers with junkyard finds; spectacular wipeouts made local guys national legends, and this mud-splattered hobby became an international craze and Olympic sport. Archival footage, rare photos and interviews with 'klunkerz' trailblazers merge in this terrific film that races downhill toward mountain-bike bliss.